The regime of ultrastrong light-matter interaction has been investigated theoretically and experimentally, using zero-dimensional electromagnetic resonators coupled with an electronic transition between two confined states of a semiconductor quantum well. We have measured a splitting between the coupled modes that amounts to 48% of the energy transition, the highest ratio ever observed in a light-matter coupled system. Our analysis, based on a microscopic quantum theory, shows that the nonlinear polariton splitting, a signature of this regime, is a dynamical effect arising from the self-interaction of the collective electronic polarization with its own emitted field.
@article{arxiv.1301.1297,
title = {Ultra-Strong Light-Matter Coupling Regime with Polariton Dots},
author = {Yanko Todorov and Aaron Maxwell Andrews and Raffaele Colombell and Simone De Liberato and Cristiano Ciuti and Pavel Klang and Gottfried Strasser and Carlo Sirtori},
journal= {arXiv preprint arXiv:1301.1297},
year = {2013}
}